"Fine tubes make fine water heater!
All-glass Evacuated Solar Collector Tube
All Glass evacuated solar collector tubes are the key component of the Solar Collectors. Each evacuated tube consists of two glass tubes. The outer tube is made of extremely strong transparent borosilicate glass that is able to resist impact from hail up to 25mm in diameter. The inner tube is also made of borosilicate glass, but coated with a special selective coating, which features excellent solar heat absorption and minimal heat reflection properties. The air is withdrawn (evacuated) from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss. Unlike other types of solar collectors, evacuated tube solar collectors still provide excellent results on cloudy days. This is because the tubes are able to absorb the energy from infrared rays, which can pass through clouds. Wind and low temperatures also have less of an effect on the function of evacuated tubes when compared to flat plate solar collectors due to the insulating properties of the vacuum.

Tube structure: All-glass double deck co-axial structure
Tube diameter (OD): 47mm, 58mm and 70mm.
Glass wall thickness: 1.60mm; 1.80mm; 2.00mm
Tube length ranges: Available from 800mm (for balcony solar system) upto 2100mm etc.
Coating material: Three-target magnetron sputtering plating CU/SS-ALN

Technical data:
1)Absorptivity a: 0.93-0.96 (AM 1.5)
2)Emittance e: Below 6.0%
3)Transmittance of glass tube T: 0.89 (AM 1.5 ISO9806-1: 1994)
4)Hail resistance: 25mm dia
5)Pressure-endure: 0.6 Mpa